In general, since a semiconductor manufacturing process for manufacturing a semiconductor device requires a high degree of precision, a high degree of cleanliness and a special manufacturing technique.
Due to the above-mentioned reason, a product having high reliability and a high degree of completion may be manufactured in a state in which the semiconductor device is completely prevented from contacting foreign substances contained in the air, i.e., a vacuum state.
Meanwhile, a vacuum pump suctioning the air and other gases in a process chamber is installed outside the process chamber to maintain the vacuum state in the process chamber for manufacturing the semiconductor device.
Also, as a vacuum valve is installed between the process chamber and the vacuum pump, and the vacuum valve is opened to discharge the air and other gasses in the process chamber and closed to maintain the vacuum state in the process chamber, the process chamber may always maintain a clean vacuum state therein.
A gate valve disclosed in the below patent document 1 (Korean Registered Patent No. 10-0338164) includes: a valve box; a valve disc disposed in the valve box to face and contact a valve sheet disposed in the valve box; a valve rod sealngly protruding to perform vertical movement and inclined movement by interposing a bellows between the inside and the outside of the valve box connected to the valve disc; and a movable unit disposed outside the valve box and allowing the valve disc to move between positions facing or not facing the valve sheet by interposing the valve rod and allowing the valve rod to perform the inclined movement so that the valve disc presses the valve sheet after the valve disc is disposed on the position spaced from and facing the valve sheet. Here, the movable unit includes: a roller disposed on each of one side and the other side of each of a piston cylinder device, a piston rod of the piston cylinder device, and the valve rod to connect each other; a spring restraining to allow a lengthy inclined hole coupled to the roller, the piston rod, and the valve rod to be spaced apart from each other in a shaft direction; and a guide provided on a cylinder of the piston cylinder device to guide the vertical movement and the inclined movement of the valve rod. When the piston rod is pressed by the piston cylinder device so that the piston rod approaches the valve rod, the valve rod is inclined by interposing the roller and the lengthy inclined hole, and the valve disc presses the valve sheet. In addition, since all mechanical components for pressing the valve disc with respect to the valve sheet are not disposed in the valve box, impurities generated by wear between components is not generated in the valve box.
However, when the valve rod vertically moves so that the valve disc is spaced apart from the valve sheet to open the valve from a state in which the valve disc presses the valve sheet to close the valve, since a front portion of the valve disc is being exposed to an inner space of the valve sheet, the air and the other gases contact an O-ring made of an elastic material and provided on the front portion of the valve disc while the air and the other gases moves inside the valve sheet, and thus the O-ring is corroded and rapidly deformed to shorten a replacement period of the O-ring.